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Vapor Lock ?

I

ievery

New member
i have a 98 Four winns 4.3 GL. I am having fuel issues. I can run all day fine and then stop in a cove for alittle while. Then crank it back up go 10 ft and it cuts off. I checked to make sure it was getting fuel and nothing not a drop. I was towed to a marina where I poured a little gas in the carborator and it took 3 tries and it cranked. It is like it loosing the pressure. Marina said it was vapor lock ? said it was the ehtanol fuel. Ihave been useing it four years. I switched to non-ethanol fuel last week when this happened. It happened again this week. If the elec fuel pump was bad, whould it not just go out at one time and not gradually ? I am going to try to locate a boat mechanic next week, my old one went out of buisness. Any suggestions on what I can try?
 
Same engine as mine, check the following.

  • Breather to fuel tank not blocked, try blowning down it, when running the engine try undoing the fuel filler cap if you can hear a sucktion, then this may be your issue its like the noise of rushing air into the tank.
  • Fuel filter (Inline) not blocked inc fuel pick up tube inside fuel tank check all hoses for secureness .( be carefull of fumes, disconnect battery.
  • if the fuel pump is noisy this is and was a sign on my boat that the fuel pump that it is failing, also inside the fuel pump on the buttom fuel pipe is a small mesh, remove and clean it.
  • check and replace your main fuel filter.
After all that check the carb jets for blockages, remove carb and get it serviced or service it yorself with a good maunal on your tybe of carb, there is a vacum pipe on the carb side, things in carb to give issue is needle valve, mixtures, and all the main jets.

lastly i dont use choke at all on my engine, it start perfect with out it, make sure you not overfueling due to a stuck choke flap.

just take caution when checking fuel issue like above a fire can happen very very quickly, you wont have to wait long and the pro"s mechanics in this forum with give you more ideas.

Hope this may help
 
Don't forget to check your anti-siphon valve. The same used to happen to me, turns out the ball bearing in the anti-siphon valve was a bit rusty and wouldn't allow gas to get through.
 
I am having the exact same problem on my 97 4.3 Volvo Penta. Cranked fine, pulling out of the marina it died. Finally got it started and it ran like a charm the rest of the day. The next day, same thing but I never got it restarted. I am very interested in your answers as I think mine has the same problem. Mine is sitting in a slip, so have no idea how to get it back on the trailer if I have to take it in.. :(
 
I would start by doing a full check on your engine starting with ignition, remember if the engine wont restart it may not be a fuel fault, there could be an ignition fault or a safty switch (kill cord switch) fault.

  1. Check condition of plugs and correct electrode gaps
  2. Check ignition leads
  3. Check coil HV leads and 12v and ground connection and redo if looks ify
  4. Check distributor cap and rotor arm, also very inportant to check is the air gap, if you have an electric spark module.

Fuel side

Dirty fuel which then gets into the carb will cause the cutting out of the engine

  1. Check for blockages and replace fuel hoses if older than a few years.
  2. Complete a full clean on the carb useing fresh petrol as this will dissolve the waxes and any grease or dirt, also check the float needle valve and adjust according to the manual, if tip of needle valve looks worn or damaged order a replacement, clean all jets with a air line and cloth over area.
  3. As mentioned before check all fuel filters and replace if old or suspect.
  4. Testing the fuel pump is possible but be very carefull, discount the fuel line to the carb inlet and attach a long piece of fuel pipe to the outlet side of the pump, place the hose in a large clear empty bottle (5ltrs minium), ask a friend to start ignition so the fuel pump runs, then monitor, if fuel flows into the bottle in a constant flow all good, if its stop starting or no fuel is pumped out then suspect a loss of 12v to the pump/relay/loom issue or a faulty pump or a blockage.
  5. Also reset the fuel/air mixture setting according to carb make and model
i would advise a manual on you engine as its critical for fault find and setting up items as to manufactures settings.

hope this may help you further
 
I am checking my fuel tank and hoses. My vent hose runs from the tank back up to the fuel cap. When I open the fuel cap to refuel, should I hear pressure ? If so, I am not. i am checking the screen on the pick up tube now and will replace all fuel hoses. Still unsure why my fuel sysyem is not staying pressurized. could it be the fuel cap ?
 
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I have cleaned or replaced everything from the gas tank to the carborator. New fuel pump and relay. Took boat out for test run last weekend and so far "knock on wood" everything is good. I cleaned the pick up screen,anti-siphon tube. I replaced the fuel line, fuel pump, and relay. Will take for a second test run today.
 
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